The present invention relates to a broadcast receiving system with a function of on-screen displaying channel information of receivable digital/analog broadcasting.
Conventionally, broadcast receiving systems such as television receivers include those OSD displaying a channel number to improve the convenience in the use for the user. By way of example, there is a display device which makes easy the check of a received channel by changing the modification of a channel number decided to be being received, with all receivable channel numbers displayed in a list on the display of CRT (for example, see Japanese Unexamined Patent Publication No. 5-236369). The decision of the receiving state in the display device is made whether an AFT (Automatic Frequency Tuning) signal outputted from a tuner is present or not within a predetermined frequency range. As an example of another device, there is a channel selection device which shifts sequentially all channels, detects the presence of broadcasting signals of each channel by the presence of a VIF (Video Intermediate Frequency) signal or a vertical synchronizing signal detected by a broadcasting detection circuit, and displays a list in which the broadcasting signals are present in which channel, thereby making easy the operation of the channel selection during channel selecting (for example, see Japanese Unexamined Patent Publication No. 55-26760). In also this selection device, the sequential channel shift is executed by controlling the frequency received by the tuner.
Meanwhile, in recent years, in addition to conventional analog broadcasting, there have been transmitted and rapidly popularized the digital broadcasting represented by the BS (Broadcasting Satellite) digital broadcasting and the CS (Communication Satellite) digital broadcasting, by which high-quality image and multi-channel are made possible. The digital broadcasting, for example, in the broadcasting according to the digital broadcasting standard ATSC (Advanced Television System Committee) of North America, is transmitted by a physical channel different from the analog broadcasting. In these digital broadcastings, there are many digital broadcastings transmitted from the same broadcasting station as that for the analog broadcasting or a broadcasting station with the same system as for the analog broadcasting. In this case, in order to improve the convenience in the use for the user who is accustomed to the channel number of the conventional analog broadcasting, the digital broadcasting has been operated such that channel selection and display can be performed by a virtual channel to which the same channel number as that for conventional analog broadcasting has been allocated.
In the digital broadcasting, there have been allocated to each channel a carrier wave having a predetermined frequency band different from that for the analog broadcasting. The channel is called a main channel, and one main channel includes a sub-channel to transmit one or a plurality of contents. The configuration of the sub-channel varies according to the broadcasting time band, and by way of example, FIG. 5 shows the configuration of the sub-channel in a time band (8:00 p.m. to 12:00 p.m.) of the main channel “4.”
According to FIG. 5, at 8:00 p.m. to 9:00 p.m., the sub-channels “0” to “4” are broadcasted; at 9:00 p.m. to 10:00 p.m., the sub-channels “0” and “1”; at 10:00 p.m. to 11:00 p.m., the sub-channels “0” to “4”; and at 11:00 p.m. to 12:00 p.m., the sub-channels “0” to “3”. Here, the channels with the sub-channel “0” (the physical channels “4-0”) are of an analog broadcasting according to NTSC (National Television Systems Committee) standard, while the channels with the sub-channels “1” to “4” (the virtual channels “4-1” to “4-4”) are of a digital broadcasting. The television programs broadcasted from the channel “4-0” are those of the conventional analog broadcasting; the SD (Standard Definition) programs broadcasted from the channels “4-1” to “4-4” are those with standard image quality of the digital broadcasting; the HD (High Definition) programs broadcasted from the channel “4-1” are those with high image quality of the digital broadcasting.
As described above, in conventional systems, the channel information of digital/analog broadcasting is displayed by executing the decision of a receiving state for each frequency band received by the tuner, so that the sequence of the channel information-screened depends on the frequency band transmitted. Therefore, even for a digital broadcasting to which the same virtual channel number as an analog broadcasting is given, the digital broadcasting has a frequency band different from the above-mentioned analog broadcasting, and thus is not displayed continuously or mixedly on one display. Hence, it is difficult for the user to understand same receivable or same-system receivable channels.
The channel structure in the digital broadcasting frequently fluctuates depending on the time band, so that only displaying simply a receivable channel makes it unclear that the broadcasting of which channel has suspended, or the broadcasting of which channel has been resumed, thereby making poor the convenience in use.
Still further, the digital broadcasting is transmitted in multi-channels, so that when all receivable channels are displayed as with conventional systems, all channels including even a channel the user does not want to see and hear will be displayed. Hence, a complex operation is imposed for the user.